Furnace damper control



Aug. 3, 1937. w FOLK 2,089,020 FURNACE DAMPER CONTROL Filed April 8, 1955 5 Sheets Sheet l ATTORNEY$ Aug. 3, 1937. I .G. w. FOLK 20 89,020

FURNACE DAMPER CONTROL Filed April 8, 1955 s Sheets-Sheet 2 l i I lll'l ll WIN/ INVENTOR.

m ezww ATTORNEYS Patented Aug. 3, 1937 UNITED; STATES PATENT, OFFICE 10 Claims.

The main objects of this invention are:

First, to provide an improved furnace damper control which is especially well adapted for controlling the operation of furnaces of the hot air type.

Second, to provide an improved differentially operable thermostatically controlled mechanical movement.

Third, to provide improved means for manually adjusting the effective relation between the dampers and theheat responsive apparatus.

Fourth, to provide in a furnace damper control an improved thermostat structure, particularly well adapted for the purpose.

;Fifth, to providea furnace damper control which is simple and economical in its parts and very -eflicient and effective in operation.

I Objects relating to details and economies of my invention will appear from the description 20 to follow. The invention is defined and pointed out inthe claims.

Preferred embodiments of my invention are illustrated in the accompanying drawings, in which:

Fig. l is afragmentary perspective view of ahot air heating system embodying features of my invention.

Fig. 2 is-an enlarged fragmentary view partially in side elevation and mainly in vertical longitudinal section through the bonnet of the furnace.

Fig. 3'is an enlargedview partially in section on a line corresponding to line 3-3 of Fig. 2.

Fig.4 is:a fragmentary viewpartialy in side 35 elevation and partially in section on line 4-4 of Fig. 3.

Fig. 5 is an-enlarged fragmentary view in side elevation of the manually adjustable means for changing the effective relation between the heat 40. responsive apparatus and the dampers.

Fig.6 is an enlarged fragmentary view in front elevation of I the manually operable end of the Bowden tube control means.

Fig. 7 is a fragmentary view mainly in side 45. elevation and partially in section of a modification. 1 Fig. 8 is an enlarged fragmentary 'view partially in side elevation and partially in section on line 88 of Fig. 9.

Fig. 9 is afrag-mentary view in transverse vertical sectionon line9-9 of Fig. 8.

In the embodiment of my invention illustrated in Figs. 1 to 6 inclusive of the drawings, I is a hot air furnace having a draft damper 2 and a 55; flue damper 3 for controlling the fire and consequently' the heat delivered by the furnace through the top or bonnet 4 thereof, the heat transfer-medium being in this case'air. lnasmuch-as furnaces ofthis general type are well no; known to those skilled in the art, it is not 116 6 sary to set forth here details of the structure or operation thereof. It is suflicient to say that the heat delivered by the furnace is increased by opening the draft damper and closing the check damper, the generated heat being reduced by closing the draft damper and opening the check damper.

In the top 4 of the furnace I dispose an elongated heat responsive element or member5 in the form of a channel opening downwardly in the path of the. heating medium traversing the furnace top, the channel being provided with longitudinal slots 6 therein and integral cross webs I provided with'alined holes 8 for a 'rod9. The heat responsive element 5 preferably has a relatively high coefficient of linear expansion while the rod 9 has a relatively low or negligible coeflicient of linear expansion. The materials which I prefer to use for this purpose are an aluminum alloy for the channel and a steel alloy for the rod.

The outer end of the rod 9 is fixed to the outer end of the element 5 by means of nuts! threaded to the rod and engaging the end web'll of the element. To support or permit free movement of the end of the elements 5 and 9, I pro-' vide a supporting bearing 12 in a wall casing I3 mounted on thebonnet. The extreme outer end I4 of the rod projects into the'wallcasing I3 and rests on thebearing I2.

The inner end of the element 5 is provided with an integral furnace bonnet escutcheon I5 having spaced side plates I6 substantially in line with the sides of the element. The escutcheon is secured to the wall of the bonnet'4, an opening I! being provided in such wall for the passage of the element 5. The escutcheon is provided with a bore I8 constituting a bearing for the cross head I9 on the inner end of 'the rod 9. Thus, the cross head I9 is free to move in the escutcheon in accordance with the expansion and contraction of the heat responsive element 5. This movement is translated to a pair of damper control levers and 2| through links 22 and 23, the levers being pivoted together and to the plates I6 at 24.

The damper control lever 20' is connected to the draft damper 2 by means including a cable 25 and a pulley 26. The damper control lever-2I- is connected to the check damper 3 by means including a cable 21 and pulleys 28 and 29. The pulley 29 is suspended by a cable 30 which is connected to the fuel supply door 3| of the furnace and is guided by pulleys 32, 33, and 34, the pulley 34 being arranged above the pulley 29. With this arrangement, the opening of the fuel supply door 3 I results in the closing of the check damper 3.

The pulleys 26 and 28 are carried at the op positeends of a pivoted hanger 35, the hanger being supported by a bracket 36 and having a crank 31 connected to one end of a Bowden tube wire 38. The other end of the wire 38 is provided with a knob 39 adapted to, be manually manipulated toadjust the position of the hanger 35. One' end' ofthe casing 4|] is connected to the bracket 33, the other end of the casing being connected to a bracket ll]. bracket 48 at the rear of the knob 39 is marked or calibrated for coaction with the knob to' indicate the degree of heat which will resultfrom results in' moving the dampers oppositely through I the pulleys 26 and 28 by changing the effective lengths of the cables and 27, the effective length of thezcable- 25 .being shortened to open the checkdamper 2 and the effective length of the cable 2'! being increased towclose the check damper 3 whenrthe 'knob' 39 is depressed to swing thehanger counterclockwise, as viewed in Fig. 1;. The Bowden'tube control means acts to hold the hanger in adjusted position, the heat responsive. apparatus then acting to maintain constant .the delivery of that heat for which theco'ntroluzis adjusted. I a A tendency of the furnace to deliver more heat,

for example is counteracted bythe differential I expansionof the heat responsive element!) relative to the rod 9, which results in ajmovement'.

ofz'the damper controlflevers ZB and- 2| acting toclose'the draftdamper 'Zand open the check.

damper 3. Thus; the heat responsive apparatus automatically maintains the desired. delivery of heat by the furnace-.

Referring to the modification'.illustrated Figs.:-'7, 8 and 9.'of the drawings', the effective" relationbetween the dampers and rod is manu ally controlled bymeans ofja crank pivoted to the end plates l6 of the jescutcheon at- '46, the

dampercontrol IEVBISrZU and 2| being pivoted to a.

pin '41 carried by the crank- 35- for movement in arcuate: slots 48 inthe-plateslfi. Otherwise, the damper' control :ap'paratus is substantially the same as that disclosed and-'described'above in connection with Figs. l' to ,6; inclusive.

In the-modification, the crank 45-,is adjusted throughand is held in' adjusted position by theBowden tube control'means, the position of" the crank governing the effective relationbetween the= cross head- 19 and'the'pivot pin 4?.- The Bowden tube control, means acts through the crank 45'to hold the pivot; pin 41 fixed in adjusted positionrelative to the moss head-l9."

The heat responsive apparatus thereupon func tions-t maintain constant the delivery of that heat for which-the control is'adjusted,-'as pointed out above. "Because of simplicity and fewer parts, I prefer'to use the structure of the modification" :for- .manuallyadjusting the effective relation between the heat responsive apparatus and the dampers controlled thereby.

Fromthe foregoing description of my invention,;it will-be apparent to those skilled in the art; that I provide, a furnace ,-damper control which; is not only simple and economical in its parts, but which is very efiicient andeffective for the purpose intended, the control being readily adjusted and-iactingto. automatically The part of the,

' ticalJ-"I have'not attempted to illustrate or course, applicable to heating systems other than 5 those using furnaces of the hot lairty'pel II have in mind hot Water and steam heating systems. llhave illustrated and described my improvements in embodiments which I find very pracdescribe other embodiments or adaptations as it is believed this disclosure will enable those skilled in the art to embody or adapt my improvements as maybe desired.

Although I have shown and described certain specific embodiments of my invention, I am fully aware that many modifications thereof. are possible. My invention is therefore not; to,- be. re stricted except insofar;as isv necessitated; by,;the prior art and by the spirit of the appended claims. 1 5,

.Having thus described my invention, whatl. claim as new and desire to secure by. Letters; Patent, is; I

1. In a furnace damper control, the ,coinbina 25;

tionof a heat responsive member of elongated. channel shape having integral ,cross webs in longitudinally spaced relation and longitudinalslots: in the top thereof andmeansfor anchoring one end of the member in the topof a furnace, the 39;

other end being free .to move, longitudinally of, the member relative to the furnacetop, the mem ber being adapted tobe disposed-with the channel opening downwardly in-thepath Qftheheatingmedium traversing 'the furnace. ztop,-said.cross 3g;

webs having alined holes, a rod arrangedthrough, said holes and having one end. fixed to the free end of said member, the coeificient of expansion of said rod being negligible compared to that of said heat responsive member, damper control 40 saidconnecting means comprising a pair-of links 5[) pivoted to said levers and said rod.

2. Ina furnace damper control, the combination of -.a heatresponsive member of elongated channel'shape having cross webs in longitudinal,-v ly spaced relation, said-cross webs havingalined holes, a rod arranged through saidholes and having one end fixed to the corresponding end of said member, the coeificient of expansion of said rod being;small compared to that of said' member, damper control levers .pivoted tothe other end of said member, and means positively connecting the otheriend of said rod to said levers so that-the longitudinalcontraction and expansion of said member is transmitted to said, damper control leversto cause movement of the latter, said connecting means comprising a pair of links pivoted to said levers and said rod.

3. -In a furnace damper control, the, combination of a heat responsive thermostatic element of elongated channel cross section adapted to be positioned face downwardly and having longitudinal slots at the topthereof an'dcross Webs in longitudinally spaced relation, saidthermo-p static element having atone, end a supporting bracket adapted for attachment-to a casing of:

a hot air furnace to support the element in horizontal relation above the top of a furnace body, said bracket comprising an escutcheon plate and a pair of spaced flanges, a rod slidably arranged in said cross webs and secured to the outer end of said thermostatic element, the thermostatic element having a relatively high coefficient of expansion as compared to said rod, control levers disposed in opposed relation and pivotally mounted between said bracket flanges, and links connecting said rod to said levers whereby the levers are positively moved oppositely through the contraction and expansion of said thermostatic element acting upon said rod.

4. In a furnace damper control, the combination of a heat responsive thermostatic element of elongated channel cross section adapted to be positioned face downwardly and having longitudinal slots at the top thereof and cross webs in longitudinally spaced relation, a rod slidably arranged in said cross webs and secured to the outer end of said thermostatic element, the thermostatic element having a relatively high coefficient of expansion as compared to said rod, control levers disposed in opposed relation, and links positively connecting said rod to said levers whereby the levers are moved oppositely through the contraction and expansion of said thermostatic element acting upon said rod.

5. In a furnace damper control, the combination of an elongated channel having longitudinal slots therein and cross webs provided with alined openings, the channel having a relatively high coefficient of linear expansion, a rod extending through said openings, the rod having a relatively low coefiicient of linear expansion, means fixing one end of said rod to the corresponding end of said channel, a cross head on the other end of said rod, the channel having a furnace bonnet escutcheon provided with spaced side plates in line with the sides of the channel, said escutcheon being provided with a bore constituting a bearing for said cross head, damper control levers pivotally connected to said side plates for movement therebetween, links connecting said cross head to said levers, and manually controlled means for adjusting the effective relation between said rod and the dampers controlled thereby through said levers.

6. In a furnace damper control, the combination of an elongated member having a relatively high coefiicient of linear expansion, an elongated member having a relatively low coefficient of linear expansion, means connecting corresponding ends of said members, a cross head on the other end of one member, damper control levers pivotally connected to said other member, links positively connecting said cross head to said levers, whereby expansion and contraction of said member will be transmitted to said levers, and manually controlled means for adjusting the effective relation between said cross head and the dampers controlled thereby through said levers, said means comprising a Bowden tube, and a crank, the position of which is adjusted through and held in adjusted position by said Bowden tube, the position of the crank governing the effective relation between said rod and the dampers.

7. In a furnace damper control, the combination of an elongated heat responsive element terminating at one end in parallel side plates having opposed arcuate slots therein, said element being in the form of -a downwardly opening channel, an adjustable crank pivoted to said side plates and having across pin extending through said slots for movement therein with the crank, damper control levers pivoted to said pin for movement between said side plates, a rod extending through said element for differential movement longitudinally of said heat responsive element, the outer end of the element being fixed to the outer end of the rod, links connecting said rod to said damper control levers so that the expansion and contraction of said element is translated to said levers, and means for manually adjusting said crank to change the position of said pin relative to said rod, said means comprising a Bowden tube.

8. In a furnace damper control, the combination of an elongated heat responsive element terminating at one end in parallel side plates having opposed arcuate slots therein, an adjustable crank pivoted to said side plates and having a cross pin extending through said slots for movement therein with the crank, damper control levers pivoted to said pin for movement between said side plates, .a rod extending through said elements for differential movement longitudinally of said heat responsive element, the outer end of the element being fixed to the outer end of the rod, links connecting said rod to said damper control levers so that the expansion and contraction of said element is translated to said levers, and means for manually adjusting said crank to change the position of said pin relative to said rod.

9. In a furnace damper control, the combination of a heat responsive element provided with parallel end plates, an adjustable crank pivoted to said end plates and having a cross pin, damper control levers pivoted to said pin for differential movement between said end plates, links connecting said element to said damper control levers so that the expansion or contraction of said element is translated to said levers, and means for manually adjusting said crank to change the position of said pin relative to said connecting means, said adjusting means comprising a Bowden tube wire.

10. In a furnace damper control, the combination of a heat responsive member, means for anchoring one end of the member in the top of a furnace, the other end being free to move longitudinally of the member relative to the furnace top, a rod having one end fixed to the free end of said member, the coefficient of expansion of said rod being negligible compared to that of said heat responsive member, damper control levers pivoted to the fixed end of said heat responsive member, and means connecting, the other end of said rod to said levers so that the movement of the free end of said member due to the longitudinal contraction and expansion of said member is transmitted to said damper control levers to cause adjustment of the latter to regulate and maintain substantially constant the heat delivered by the furnace through its top, said connecting means comprising a pair of links pivoted to said levers and said rod.

GEORGE W. FOLK. 

